Electric furnace



June 26, 1928.

M. UNG ER ELECTRIC FURNACE Filed Dec. 1926 Fig 1.

2 Q nw m m r o t .T m; A N MS as H a M a PM June 26,1928.

'vision of a simple, reliable electric circulation of molten metal and adesira is power factor.-

UNITED sr 'rss 1,675,237 PATENT OFFICE.

n3! UNGEB, 01' PIT'ISIIEIib, IASSLCHUBETTS, ASSIGHOB TO GENERAL ELBGIBIC COIPANY, A CORPORATION 01' NEW YORK. I

ELECTRIC FURNACE.

Application filed December 9, 1926. Serial Io. 158,640.

My invention relates to electric furnaces, more particularly to electric metal melting furnaces, and has for its object the pronace' having a satisfactor llore particularly my invention relates to electric metal melting furnaces of the induction type, ahd more especially to ring p in induction furnaces in which the charge 1: contained in a ring-shaped reservoir or channel withwhich is associated a primary winding for inducing heating currents in furnaces, it is necesgreat the charge. In such to make the channel of relativel Sllg' wi th so that the furnace can be c .arged with pieces of metal of convenient size.

' Ordinaril therefore, the ring-shaped channel is re atively wide and shallow, *This has thedisadvantage that certain portions of the charge are situated in a comparatively remote position with respect to the primarylwinding so that poor'interlinkage of the magnetic flux with these portions necessarily results with-a consequent lowpower factor for the furnace. This limitation as to power factor greatly limits the size of the furnace. p

' In carrying out my invention I provide adeep narrow channel at the bottom of the ring-shaped reservoir in which a portion of the charge forms a closed secondary circuit for a primary coil associated therewith. For a more complete understanding of my invention reference should be had to the accompanying drawing, in which Fig. 1 is a sectional view of an electric metal melting furnace embodying my invention, while Fig. 2 is asectional view alon 2-2 of F ig.- llooking in the dlrection of the arrows.

Referring to the drawing, my invention in one form embodies an annuilar furnace"- crucible 10 made of a suitable eat refractory material, such as fire clay, which may be molded or otherwise shaped. ThiSCl'llClble is provided with a horizontal ringshaped reservoir 1-1 for the charge and with 'an annular channel 12 situated below the reservoir. v

As shown in Fig. 1, this channel 12 comthe line municates with the inner periphery of the reservoir so as to closely surround a primary winding 13 inserted in the channel and mounted on a suitable magnet core 14. The (prlmafiy winding is preferably displace axia yin a downward directionwith respect to the channel '12. As shown in Fig. 1, it will be observed that the top of the electromagnetic repulsion acting on the metal in the channel and in order to facilitate the circulation, the annular channel rimary coil and the top of the channel are preferably is made with a smaller diameter at the bottom so that it extends obliquel ugt e ward substantially along the line 0 resultant of the radial and axial re ulsive forces. Phis arrangementof the c annel tends to promote circulation of the charge.

In order to provide for the return of charge from the reservoir hack to the channel two oppositely disposed ooves or channels 15 and 16 are provided in the crucible-through which the charge returns in a downward direction, as indicated by the arrows. These channels connect the outer periphery of the reservoir with the bottom of the channel and provide areturn path for the molten charge through a region which is remotely situated from the primary winding. A rtion of the charge may also return by owing downward along the inner periphery of the reservoir and. channel, as indicated by the arrows 17. This will depend u n t e arrangement of the primary win 'ng and other details of construction.-

An annular cover 18 is provided for the crucible,'the upper cross bar 14"of the core being removable to permit. the cover to be removed.

While I have described my invention as embodied in concrete form' and as operating in a specific manner in accordance with the 20 reservoir, and a priming tlvely assoclated with sail induceheating currents in the portion ofcan withvsaid reservoir at the inner periphery.

l6 thereofland a primer winding inductively associated with said 0 ennel. v I

v 2. An electric furnace comprising a crui I cibleprovidin a ring-shaped reservoirend an annular c ennel depending from seid winding induce channel so. as to thew charge contained therein, soid primary winding being exially displaced with respect 5 to saidichannel to' produce scirculetion of charve between {the channel (and reservoir by electromagnetic repulsion; I 4 3. An electric furnace comprising scruecible providing e horizontal ring-shaped 39 reservoir and a horizcntelnnnuler channel depending from the reserroirand communictr-tin with, the reservoir 7 at the inner r perip ery thereof, a pri'inzii'ywindingconcentrically located with respect to said chan- 35 'nel for inducing heating currents in a portion of the char e contained therein, said primary winding eing displaced in a downfrom the bottom of said reservoir and com- "deep narrowj ring-she tion in said channel by electromagnetic} I s i 1 newest ward direction with respect to said soas'to produce a circuietion of charge he tween, said channel and said reservoir.

4. An electric furnace comprising at cmcible providin a horizontal rin -sheped reservoir for t e charge and t relatively deep narrow annular channel depending municati'ng therewith at the inner periphery thereof, onde' primary winding associated with saidchannel so astoproducea how of charge in saidchennei in an upward direction intd said reservoir, said crucible being provided with a return path forthe inoiten charge throu h air-region remotefroin seid primarywining. I

,5. An eiectric furnace coin rising e crucible providin a; horizont ring-shaped 65 reservoir for fiiechar e and e rcletiveiy v pe -channel depending from the bottom of said reservoir and conim'uniceting therewith at the inner periphery thereof, and u'nrimary winding inductively associated 'Wit said channel and oxisll displaced in a downward direction with. respect toysaid channel so as to produce circulation of charge in an upward direcrepulsion, said crucible being provided with a return path for the charge connecting v outer periphery of said reservoir with bottom of said channel.

In witness whereof, I have hereunto set iny hand this. seventh'dey of December,

, ninet es sire-zen. 

